[master] Moved reading of file signature into png_read_sig (Cosmin)

CHANGES

@@ -2702,13 +2702,9 @@ version 1.4.5rc01 [November 19, 2010]
 
 version 1.4.5rc02 [November 20, 2010]
   Removed some extraneous parentheses that appeared in pngrutil.c of
-    libpng-1.4.3bet01
+    libpng-1.4.3bet01 (Cosmin)
-
-version 1.4.4-optipng [November 14, 2010]
-  Fixed atomicity of chunk header serialization (Cosmin)
-  Added test for io_state in pngtest.c (Cosmin)
-  Moved reading of file signature into png_read_sig (Cosmin)
   Revised png_get_uint_32, png_get_int_32, png_get_uint_16 (Cosmin)
+  Moved reading of file signature into png_read_sig (Cosmin)
 
 */ }
 #endif

png.h

@@ -2649,11 +2649,12 @@ PNG_EXPORT(png_bytep,png_get_io_chunk_name)
       ((png_uint_32)(*((buf) + 2)) << 8) + \
       ((png_uint_32)(*((buf) + 3))))
 #  define png_get_uint_16(buf) \
-     (((png_uint_32)(*(buf)) << 8) + \
+     ((png_uint_16) \
-      ((png_uint_32)(*((buf) + 1))))
+      (((unsigned int)(*(buf)) << 8) + \
+       ((unsigned int)(*((buf) + 1)))))
 #  define png_get_int_32(buf) \
      ((png_int_32)((*(buf) & 0x80) \
-      ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffff)+1)) \
+      ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
       : (png_int_32)png_get_uint_32(buf)))
 #else
 PNG_EXPORT(png_uint_16,png_get_uint_16) PNGARG((png_bytep buf));

pngread.c

@@ -214,35 +214,13 @@ void PNGAPI
 png_read_info(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_read_info");
- 
+
    if (png_ptr == NULL || info_ptr == NULL)
       return;
- 
-   /* If we haven't checked all of the PNG signature bytes, do so now. */
-   if (png_ptr->sig_bytes < 8)
-   {
-      png_size_t num_checked = png_ptr->sig_bytes,
-                 num_to_check = 8 - num_checked;
-
-#ifdef PNG_IO_STATE_SUPPORTED
-      png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
-#endif
-
-      png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
-      png_ptr->sig_bytes = 8;
-
-      if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
-      {
-         if (num_checked < 4 &&
-             png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
-            png_error(png_ptr, "Not a PNG file");
-         else
-            png_error(png_ptr, "PNG file corrupted by ASCII conversion");
-      }
-      if (num_checked < 3)
-         png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
-   }
 
+   /* Read and check the PNG file signature. */
+   png_read_sig(png_ptr, info_ptr);
+  
    for (;;)
    {
       PNG_IHDR;
@@ -426,7 +404,7 @@ void PNGAPI
 png_read_update_info(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_read_update_info");
- 
+
    if (png_ptr == NULL)
       return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
@@ -448,7 +426,7 @@ void PNGAPI
 png_start_read_image(png_structp png_ptr)
 {
    png_debug(1, "in png_start_read_image");
- 
+
    if (png_ptr == NULL)
       return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
@@ -465,10 +443,10 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
       0xff};
    PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
    int ret;
- 
+
    if (png_ptr == NULL)
       return;
- 
+
    png_debug2(1, "in png_read_row (row %lu, pass %d)",
       (unsigned long) png_ptr->row_number, png_ptr->pass);
 
@@ -724,7 +702,7 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
    png_bytepp dp;
 
    png_debug(1, "in png_read_rows");
- 
+
    if (png_ptr == NULL)
       return;
    rp = row;
@@ -775,7 +753,7 @@ png_read_image(png_structp png_ptr, png_bytepp image)
    png_bytepp rp;
 
    png_debug(1, "in png_read_image");
- 
+
    if (png_ptr == NULL)
       return;
 
@@ -813,7 +791,7 @@ void PNGAPI
 png_read_end(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_read_end");
- 
+
    if (png_ptr == NULL)
       return;
    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
@@ -993,7 +971,7 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 #endif
 
    png_debug(1, "in png_destroy_read_struct");
- 
+
    if (png_ptr_ptr != NULL)
       png_ptr = *png_ptr_ptr;
    if (png_ptr == NULL)
@@ -1069,7 +1047,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr,
 #endif
 
    png_debug(1, "in png_read_destroy");
- 
+
    if (info_ptr != NULL)
       png_info_destroy(png_ptr, info_ptr);
 

pngrutil.c

@@ -69,6 +69,39 @@ png_get_uint_16 (png_bytep buf)
 }
 #endif /* PNG_USE_READ_MACROS */
 
+/* Read and check the PNG file signature */
+void /* PRIVATE */
+png_read_sig(png_structp png_ptr, png_infop info_ptr)
+{
+   png_size_t num_checked, num_to_check;
+
+   /* Exit if the user application does not expect a signature. */
+   if (png_ptr->sig_bytes >= 8)
+      return;
+
+   num_checked = png_ptr->sig_bytes;
+   num_to_check = 8 - num_checked;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
+#endif
+
+   /* The signature must be serialized in a single I/O call. */
+   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
+   png_ptr->sig_bytes = 8;
+
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   {
+      if (num_checked < 4 &&
+          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+         png_error(png_ptr, "Not a PNG file");
+      else
+         png_error(png_ptr, "PNG file corrupted by ASCII conversion");
+   }
+   if (num_checked < 3)
+      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
+}
+
 /* Read the chunk header (length + type name).
  * Put the type name into png_ptr->chunk_name, and return the length.
  */
@@ -79,32 +112,31 @@ png_read_chunk_header(png_structp png_ptr)
    png_uint_32 length;
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that the chunk header is being read.
-    * PNG_IO_CHUNK_HDR requires a single I/O call.
-    */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
 #endif
 
-   /* Read the length and the chunk name */
+   /* Read the length and the chunk name.
+    * This must be performed in a single I/O call.
+    */
    png_read_data(png_ptr, buf, 8);
    length = png_get_uint_31(png_ptr, buf);
 
-   /* Put the chunk name into png_ptr->chunk_name */
+   /* Put the chunk name into png_ptr->chunk_name. */
    png_memcpy(png_ptr->chunk_name, buf + 4, 4);
 
    png_debug2(0, "Reading %s chunk, length = %lu",
       png_ptr->chunk_name, length);
 
-   /* Reset the crc and run it over the chunk name */
+   /* Reset the crc and run it over the chunk name. */
    png_reset_crc(png_ptr);
    png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
 
-   /* Check to see if chunk name is valid */
+   /* Check to see if chunk name is valid. */
    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that chunk data will (possibly) be read.
+   /* It is unspecified how many I/O calls will be performed
-    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
+    * during the serialization of the chunk data.
     */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
 #endif
@@ -185,11 +217,10 @@ png_crc_error(png_structp png_ptr)
    }
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* Inform the I/O callback that the chunk CRC is being read */
-   /* PNG_IO_CHUNK_CRC requires the I/O to be done at once */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
 #endif
 
+   /* The chunk CRC must be serialized in a single I/O call. */
    png_read_data(png_ptr, crc_bytes, 4);
 
    if (need_crc)
@@ -3108,17 +3139,10 @@ png_read_finish_row(png_structp png_ptr)
          {
             while (!png_ptr->idat_size)
             {
-               png_byte chunk_length[4];
-
                png_crc_finish(png_ptr, 0);
-
+               png_ptr->idat_size = png_read_chunk_header(png_ptr);
-               png_read_data(png_ptr, chunk_length, 4);
-               png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
-               png_reset_crc(png_ptr);
-               png_crc_read(png_ptr, png_ptr->chunk_name, 4);
                if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
                   png_error(png_ptr, "Not enough image data");
-
             }
             png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
             png_ptr->zstream.next_in = png_ptr->zbuf;